4L60E Differences

FearlessAZ

Well-Known Member
I was reading through somewhere that the bellhousing on our platform is slightly different than a normal 4L60E. Is this true? Are there any other noticeable differences?

I was spitballing the idea of possibly pulling the one out of my 04 TB to put into an older vehicle. I know other changes need to be made.
 

Mooseman

Moderator
Yes, the bellhousong is different for the 4.2 as well as the torque converter bolt pattern. Not sure if they differ for the LS engine.
 

MRRSM

Lifetime VIP Supporter
This is an interesting On Topic Article covering many of the differences:

 
OP
OP
FearlessAZ

FearlessAZ

Well-Known Member
Both good info.

So reading that article, would just have to swap bellhousing to physically bolt up to a Gen 1 SBC. Would just need to look at the input shaft and converter.
 

Mooseman

Moderator
There might have been some differences in internal electronic controls that would prevent you, for example, to install a later model trans in an earlier year truck. I think as long as the connector is the same, it should work along with the bellhousing and converter swap.
 
OP
OP
FearlessAZ

FearlessAZ

Well-Known Member
I should have been more specific.

I am playing with the idea of putting this in my 1970 Impala with a 400ci SBC. Not too worried about electronics cause a stand alone unit would handle all that.
 

Mooseman

Moderator
Sounds like a cool project. You shouldn't any problems then to make it work.
 

Dr.Fiero

Well-Known Member
Remember that in 07/08 (not dead sure of the switch year), they added a pressure sensor lead. The connectors were the same, but a different color.

Doesn't totally apply to you, but... you can use a late model in an early, but not the other way around.
 

Reprise

Lifetime VIP Supporter
Probably some driveshaft work, as the 4L60 housing is different length than the TH350 or TH400 that was originally in that car. But I'm almost positive the proper bellhousing will bolt up to a SBC.

You may need to match SBC flexplate bolt pattern to the correct torque converter for the application. Since the 4L60 is based off the TH350, you're probably OK w/ regard to the dimensions of the transmission tunnel in the Impala chassis (e.g.; height / width). I'd still measure beforehand, but you'll prolly have plenty of room. You might have to mod the shift linkage; be prepared for that.

There are resources online that will describe all of this (except for the Impala's tunnel dimensions.) Find at least two different sites that match info before you start searching for parts. There are also some minor variations internally in the 4L60, but most of the bigger changes came in 2005-up. Nothing that should affect you, unless you start modding the trans - then you need to know the vintage (and you do, so you're good).

IIRC,1999-2003 is a breakpoint for 4L60s; before you put the trans in the Impala, grab the ID codes off the trans housing. GM wasn't above putting in older / newer parts in vehicles, depending on what time of year the vehicle was built & what parts were in the bins, etc. So depending on when yours was built, you could have an '03, an '04, or even an '05-spec 4L60 (this would be rare, but if you have a late '04 build (per the driver's door label), it's worth validating).

If that 400 SBC has been built with high HP, consider beefing up the internals on the 4L60; GM built them with more and more plastic parts as time went on. Properly built, they are supposed to be good to about 700HP max.

If the motor is stock, you should be OK with the trans as-is, internally (you already know you need a controller for the trans, as well as a new torque converter & bellhousing). Properly cared for and not abused, a 4L60 can last about 200K or a little longer (although I'd at least put a TransGo corrective shift kit in (orange box) and maybe some metal accumulator pistons in the valve body (in place of the plastic ones) to help get to that 200K).

There are plenty of 4L60s in old F-body cars, as an example, and many of them still have SBCs installed. So it's definitely do-able; you just have a little homework to do. You'll probably need to input the rear diff ratio into the controller programming, I would guess.
 
OP
OP
FearlessAZ

FearlessAZ

Well-Known Member
The only mods to the Impala at this time are Holley Sniper efi, Edelbrock RPM Air gap, and custom exhaust. It will eventually run to about 500hp once the motor is rebuilt and gone through but this is a couple years off.

The 4l60E in the TB was rebuilt about 3 years ago and maybe has 30k on it. There was a thread I made on here when it was done. It does have the shift kit and the servo upgraded. I would have to dig up the old invoice to see exactly what was done and what brands.

From my reading, it seems to need a bellhousing swap (haven't looked to see where the I6 housing would line up), stand alone TCU, cross member moved, shortened drive shaft, speedo (I plan on converting to Dakota Digital) and I think something like the TCI Remote TPS.
 

Online statistics

Members online
11
Guests online
197
Total visitors
208

Forum statistics

Threads
19,643
Messages
583,286
Unanswered questions
1
Answered questions
1
Members
12,373
Latest member
Rob65
Top Bottom